Device correcting the amount of fuel injected into an internal combustion engine



May 21, 1968 M. DANGAUTHIER 3,384,060

DEVICE CORRECTING THE AMOUNT OF FUEL INJECTED INTO AN INTERNAL COMBUSTION ENGINE will IIIIIHIII Filed Nov. 25, 1965 mw ,r IZ

United States Patent O s claims. (l. 12s-139) io ABSTRACT OF THE DSCLOSURE A device for correcting the fiow of fuel injected into an internal combustion engine by an injection pump, said device comprising two chambers separated by a movable wall which is operatively connected to the injection pump to vary the fuel flow from the latter, one of the chambers communicating with the downstream side of the air ad- 0 mission throttle in the induction pipe of the engine and the other chamber being partly defined by a water jacket connected by inlet and outlet pipes to the engine cooling water circuit, a valve being inserted in one of the inlet and outlet pipes to control the rate of flow of the cooling liquid.

The present invention relates to a device correcting the richness of the air-.fuel mixture in an injection engine and more particularly a petrol or gasoline injection engine in which the regulation is effected by suction means.

Petrol injection engines must comprise extremely precise automatic means regulating their richness as a function of the parameters of engine speed and load, since firstly these engines must sustain their reputation of high etiiciency and7 secondly, the percentages of harmful gas (carbon monoxide in particular) contained in the exhaust are affected to a considerable extent by this richness.

In an injection engine having a suction-actuated regulation of the most conventional type the metering of the amounts of fuel injected is effected, for example, by the position of equiiibrium assumed by a diaphragm subjected, on one side, to the absolute pressure prevailing in the induction pipe and, on the other side, to the surrounding pressure; the force resulting from the difference between these pressures is equal to thatY of an opposing tension or compression spring.

In this way, there corresponds to an absolute pressure in the induction pipe (which determines the volume of air drawn in per cycle) a welldetermined position of this diaphragm and a certain amount of fuel injected, their correlation being insured by a simple mechanical device.

If it is now exam-ined what happens when the atmospheric pressure changes, it is clear that for a given absolute induction pressure, the pressure differential force acting on the diaphragm changes and the position of equilibrium is no longer the same. The initial value of the richness is not maintained.

One solution consists in applying on the side opposed to the induction pressure side, a constant pressure pro- 60 duced by means of a sealed enclosure having such size that variations in volume produced by the movement of the diaphragm are negligible.

This solution solves the problem from the point of view of variations in outside pressure that this reserve of pressure is also responsive to the surrounding temperature.

Thus a change in the temperature of the corrector results. proportionally to the absolute temperatures, in a modification in the reference pressure which consequently modifies all the flows by a constant amount whereas this Patented May 21, 1968 lCe amount should remain proportional to the induction pressure. This results for partial loads in an enrichment when the temperature drops and an excessively poor mixture when -it rises.

To remedy this drawback, a compromise between the pressure correction and the temperature correction is needed.

The object of the linvention is therefore to provide a device for maintaining the proportions of the air-fuel mixture at fixed values, the correction of the richness in accordance with variations in surrounding pressure and temperature being effected in the same element but independently of each other. This device also provides, owing to its very arrangement, a richer mixture when starting up and heating the engine (putting into action).

The device according to the invention comprises a hermetically sealed first chamber containing a constant mass of air, and a second chamber sealed from the first chamber and connected to a pressure take off placed in the induction tube of the engine on the downstream side of the air admission throttle of the engine, said chambers being so arranged that a variation in the Volume of one results in a reciprocal variation in the volume of the other and in a variation in the flow from the injection pump of the eng-ine, said device further comprising means responsive to the temperature lof the engine and to a temperature which is suitably selected (for example ternperature under the engine bonnet, surrounding tempera ture, temperature of the induction air), said means acting on the temperature of the mass of air enclosed in the first chamber.

Further features and advantages of the invention wil be apparent from the ensuing description with reference to the accompanying drawing to which the invention is in no way limited.

ln the accompanying drawing, the single figure is z diagrammatic sectional view of a correcting device ac cording to the invention.

In the illustrated embodiment, the device is house( principally in a case 1 comprising a body 1A closed by t cap 1B, these two members being assembled by flange: 2A, 2B clamped together by screws or bolts (not shown) Clamped between these two fianges is the edge of a rolling diaphragm 3 which defines with the inner wall of the ca; a first chamber 4 which can be connected to the atmos pliere by way of an aperture 5 normally closed by z screw 6.

The wall of the cap 1B comprises a cavity or wate: jacket 7 fed by way of an inlet pipe 7E and an outlet pipf 7S which communicate with the cooling system of th engine (not shown). The circulation of the fluid is regu lated by a thermostat valve 8 responsive to a carefully chosen temperature which can correspond, for example to the temperature prevailing under the bonnet of thi engine, the temperature of the atmosphere surrounding the vehicle or the temperature of the induction air. Th outer wall of the cap 1B is provided with fins 9.

The body 1 of the case comprises a transverse partitioi wall 10 which defines with the diaphragm 3 a secon( chamber 11 communicating by way of a pipe 12 with z pressure take-off 13 located in the divergent part 14 of Venturi whose neck 16 contains the conventional throttl 17 controlling the admission of air into the induction pipi 18 of the engine (not shown).

The partition wall 1t) is provided with an aperture 1! in which is slidable a rod 2G of a piston 21 housed in thi second chamber 11 and connected to the diaphragm 3 Disposed between the partition wall 10 and the piston 21 around the piston rod 20 is a helical compressioi spring 22.

The free end of the rod Z acts on the control system :ontrolling the ow or output of an injection pump com- )rising in the known manner a plunger 23 controlled by a )ush-rod 24 actuated by a rotary cam 25, variation in the [mount of combustible fluid injected for each stroke of he piston 23 being achieved by varying the position of a 'eturn abutment 26 stopping the return movement of the iiston. This return movement is produced by the action )f a spring 27. The abutment 26 is constituted by a lever vhich is pivotably -mounter at 28, the free end of the lever :omprising a curved ramp 29 of suitable profile against vhich bears the end of the rod 20, the latter being profided with two balls one of which, 30a, rolls on the ramp vhereas the other, 30b, rolls on a rectilinear supporting 'unway rigid with the case.

The device operates in the following manner:

Correction in accordance with surrounding pressure There will rst be considered the case of a basic reguation of the device, that is, for a hot engine and for urrounding conditions of pressure and temperature existng when determining the prole of the ramp 29.

For a given induction pressure in the pipe 18, equilib- 'ium of the rod 2G and of the piston 21 is achieved when he force under the diaphragm 3 (chamber 11) correponding to this pressure equals and opposes the algebraic um of the force of the pressure in the chamber 4 and the oree 'exerted by the spring 22. The last two forces both lepend on the position of the diaphragm, that is, the torce due to the pressure in the chamber 4 depends on he relation between the initially determined Volume (in he basic conditions of pressure and temperature) and the 'olurne the chamber' defines in the case under consideraion. The force of the spring 22 is determined by its lexibility.

It can be seen that the vchamber 4 performs the funcion of a tension spring having a hyperbolic characterisio (PV=c0nstant) to which is added the linear force if the spring 22.

IIt should be noted that the addition of the spring 22 is tot fundamental to good operation of the device. It is nerely provided to modify the hyperbolic curve of the lisplacement of the piston 21 as a function of the inducion pressure so as to diminish the large variation in the lope of this curve between the two ends of the travel, his slope determining the sensitivity of the ilow of fuel )r output of the pump P for the slightest variation in aressure.

As compared to known devices, which comprise only t spring and a diaphragm communicating with the surounding pressure (or with a constant reference preslure), the arrangement according to the invention pernits:

(a) Considerably reducing the maximum pressure lifference between the two sides of the diaphragm, this iiierence being the smaller as the force of the spring Z2 is smaller. This considerably facilitates the problem )f the seal between the two chambers 4 and l1.

(b) Reducing the energy to be furnished by the spring 1nd therefore its size or, for given dimensions, increasng the absolute precision of its rating.

(c) Easily controlling the temperature of chamber i owing to its small size.

If the temperature of the chamber 4 is maintained :onstant (by maintaining the position of the valve S :onstant) the explanation given hereinbefore shows that :he equilibrium of the piston 21 only depends on the induction pressure in the pipe 18. The initial value of :he richness is thus well maintained irrespective of the surrounding pressure.

Sorrecz'on in accordance with varialion in temperature A change in temperature can only modify the flow or Jutput of the pump by its effect on the air contained in :he chamber 4.

It has been shown that when a change in temperature occurs in the mass of air in the chamber 4, the correction of the flow of fuel is proportional to this temperature change. The temperature in the chamber 4 is determined by that of the water in the jacket 7. The ternperature of this water can vary between the temperature surrounding the water jacket or cap 1B (valve 8 closed) and the temperature of the liquid in the main cooling circuit of the engine in operation (valve 8 wide open).

This control of the temperature in the chamber 4 thus permits exactly adjusting, diminishing as desired, or rendering nil the theoretical correction of the ow due to a variation in the surrounding temperature without diminishing the exactness of the correction as a function of the outside pressure, since the foregoing does not infirm the deductions given hereinbefore.

Automatic enrichment when starting up the engine An automatic enrichment when starting up the engine occurs in a similar manner to the correction of the flow as a function of the surrounding temperature. Indeed, irrespective of the correlation retained between the temperature imposed on the mass of air and the temperature of the cooling liquid, it is obvious that when starting up with a cold engine, the low temperature of the cooling liquid corresponds to the low temperature of the mass of air and that consequently the equilibrium of the moving part which is constituted by the diaphragm 3 and piston 21 and depends on the pressure of this mass of air, is achieved for a smaller volume of air and therefore for a larger ow of fuel.

Thus, the gaseous induction mixture is naturally enriched right from the start and the enrichment disappears gradually with the heating up of the engine until a return to the basic regulation of the device is reached.

Although specific embodiments of the invention have been described, many modifications and changes may be made therein without departing from the scope of the invention as dened in the appended claims.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

1. Device for correctingr the ow of fuel injected into an internal combustion engine by an injection pump of the volumetric type in accordance with variations in the surrounding conditions, the engine having a cooling liquid circuit, an induction pipe and an air admission throttle in said pipe, said device comprising a movable wall and a rigid wall defining a hermetically sealed first chamber containing a constant mass of air, a second chamber, said movable wall sealing the second chamber off from the first chamber and insuring that variation in the volume of one of said chambers results in a reciprocal variation in volume of the other of said chambers, passage means adapted to -put the second chamber in communication with said induction pipe on the downstream side of said air admission throttle, means operatively connecting said movable wall to said injection pump so as to vary the flow from said injection pump with variation in the position of said movable wall, a `cavity in said rigid wall, an inlet pipe and an outlet pipe communicating with said cavity for putting said cavity in communication with the cooling liquid circuit of the engine, and a valve in one of said inlet and outlet pipes for controlling the rate of flow of the cooling liquid from the cooling liquid circuit through said cavity, whereby the temperature of said rigid wall and consequently the temperature and pressure of the air in said rst chamber are responsive to the temperature of the cooling liquid to an extent depending on the action of said valve.

2. Device as claimed in claim 1, wherein said Inovable wall is a rolling diaphragm, the device further comprising a piston operatively connected to the diaphragm and a rod regulating the flow of said pump and operatively connected to said piston.

3. Device as claimed in yclaim 2, comprising a compression spring interposed between a wall partly defining the second chamber and one side of said piston.

4. Device as claimed in claim 1, wherein said valve is a thermostat valve exposed to the temperature of an atmosphere outside said device.

5. Device as claimed in claim 1, further comprising outer heat-dissipating lins on said rigid Wall of the rst chamber.

References Cited UNITED STATES PATENTS 2,876,755 3/1959 Gold et al. 123-111 3,006,329 10/1961 Armstrong et al. 12S-139.1' 3,169,513 2/1965 Hennequin 12S-140.

LAURENCE M. GOODRIDGE, Primary Examiner. 

